WordPress – Taxonomy single navigation order by custom field

i’ve an issue here.

I like to show 2 navigation buttons in single.php, based in a taxonomy(Tax name: temporada)

Now i google it. I found a simple code to show this buttons but, this are order by date, i like to order this, but custom field (custom field: numeroepisodio)

This is my code:

functions.php

add_filter( 'get_next_post_join', 'navigate_in_same_taxonomy_join', 20);
add_filter( 'get_previous_post_join', 'navigate_in_same_taxonomy_join', 20 );

function navigate_in_same_taxonomy_join() {
    global $wpdb;
return " INNER JOIN $wpdb->term_relationships AS tr ON p.ID = tr.object_id INNER JOIN $wpdb->term_taxonomy tt ON tr.    term_taxonomy_id = tt.term_taxonomy_id";
}

add_filter( 'get_next_post_where' , 'navigate_in_same_taxonomy_where' );
add_filter( 'get_previous_post_where' , 'navigate_in_same_taxonomy_where' );

function navigate_in_same_taxonomy_where( $original ) {
    global $wpdb, $post;
    $where = '';
    $taxonomy   = 'temporada';
    $op = ('get_previous_post_where' == current_filter()) ? '<' : '>';
    $where = $wpdb->prepare( "AND tt.taxonomy = %s", $taxonomy );
        if ( ! is_object_in_taxonomy( $post->post_type, $taxonomy ) )
    return $original ;

    $term_array = wp_get_object_terms( $post->ID, $taxonomy, array( 'fields' => 'ids' ) );
    $term_array = array_map( 'intval', $term_array );

        if ( ! $term_array || is_wp_error( $term_array ) )
    return $original ;
    $where = " AND tt.term_id IN (" . implode( ',', $term_array ) . ")";
return $wpdb->prepare( "WHERE p.post_date $op %s AND p.post_type = %s AND p.post_status = 'publish' $where", $post->    post_date, $post->post_type );
}

single.php

<?php if ( get_previous_post() != null ) : ?>
<?php
$singular_nav_previous_text = apply_filters( 'tc_singular_nav_previous_text', _x( '&larr;' , 'Previous post link' , '    customizr' ) );
    previous_post_link( '%link' , '<div id="temporadas-dropdown"><i class="fa fa-caret-left"></i> ANTERIOR</div>' );
?>
<?php endif; ?>

<?php if ( get_next_post() != null ) : ?>
<?php
$singular_nav_next_text = apply_filters( 'tc_singular_nav_next_text', _x( '&rarr;' , 'Next post link' , 'customizr'     ) );
    next_post_link( '%link' , '<div id="temporadas-dropdown">SIGUIENTE <i class="fa fa-caret-right"></i></div>' );
?>
<?php endif; ?>

How can display the buttons based in taxonomy = 'temporada' and order by meta_value = 'numeroepisodio'?

Thanks for your time.